Conventionally, a coil unit has been known which includes four coils and a holder which holds the four coils (see, for example, Japanese Patent Laid-Open No. 2015-225943). In the coil unit described in the Patent Literature, a side-face pair comprised of a pair of side faces parallel to each other is formed on an outer peripheral face of a holder, and the outer peripheral face of the holder is structured of two side-face pairs. In other words, the outer peripheral face of the holder is structured of four side faces each of which is formed in a flat face shape. Each of the four side faces is formed with a protruded part protruding to an outer side of the holder, and a coil is directly wound around the protruded part. Two coils which are respectively wound around the protruded parts of two side faces structuring one of the two side-face pairs are structured by using one conducting wire. Similarly, the remaining two coils which are respectively wound around the protruded parts of two side faces structuring the other of the two side-face pairs are also structured by using one conducting wire.
In the coil unit described in the Patent Literature, when the coil wound around the protruded parts of one of the two side-face pairs is referred to as a first coil and the coil wound around the protruded parts of the other of the two side-face pairs is referred to as a second coil, in this coil unit, for example, after two first coils are directly wound around the protruded parts, two second coils are directly wound around the different protruded parts. In this case, when a crossover wire serially-connecting two first coils is not appropriately arranged, the crossover wire and the second coil may be overlapped with each other and thereby it may be occurred that the second coil is not orderly wound around.